frr: fix compilation with GCC14

[httpstorm]

Fixes:

zebra/zebra_netns_notify.c: In function 'zebra_ns_ready_read': zebra/zebra_netns_notify.c:265:40: error: implicit declaration of function 'basename' [-Wimplicit-function-declaration]
  265 |         if (strmatch(VRF_DEFAULT_NAME, basename(netnspath))) {
      |                                        ^~~~~~~~

Maintainer: @lucize
Compile tested: WRT3200ACM

Another pending PR: #24083

@neheb @robimarko @PolynomialDivision @1715173329 @trippleflux

[neheb]

I would check if netnspath is writable.

[httpstorm]

@neheb
Good catch. According to the macOS man page for basename

basename() returns a pointer to internal static storage space that will be overwritten by subsequent calls.
Other vendor implementations of basename() may modify the contents of the string passed to basename(); this should be taken into account when writing code which calls this function if portability is desired.

Edit: according to https://man7.org/linux/man-pages/man3/basename.3.html

There are two different versions of basename() - the POSIX
       version described above, and the GNU version, which one gets
       after

               #define _GNU_SOURCE         /* See feature_test_macros(7) */
               #include <string.h>

       The GNU version never modifies its argument, and returns the
       empty string when path has a trailing slash, and in particular
       also when it is "/".  There is no GNU version of dirname().

       With glibc, one gets the POSIX version of basename() when
       <libgen.h> is included, and the GNU version otherwise.

So if we include libgen.h, we switch from the GNU version that does not modify the argument to the POSIX version which does. And we are likely to break frr. I will change the PR to draft, until we decide what to do. Any suggestions?

I analysed a part of the code path: we start with void *arg which is assigned to struct zebra_netns_info *, where const char *netnspath; is not writable. This is assigned to const char *netnspath; and passed to basename. So if basename tries to update netnspath, bad things may happen. I think it's worth reporting upstream. Edit: the same applies to branch master.

struct event {
	…
	void *arg;		      /* event argument */
	…
};
…
struct zebra_netns_info {
	const char *netnspath;
	unsigned int retries;
};
…
int strcmp(const char *s1, const char *s2);
…
#define strmatch(a,b) (!strcmp((a), (b)))
…
#define EVENT_ARG(X) ((X)->arg)
…
struct zebra_netns_info *zns_info = EVENT_ARG(t);
const char *netnspath;
…
netnspath = zns_info->netnspath;
…
if (strmatch(VRF_DEFAULT_NAME, basename(netnspath))) {

https://github.com/FRRouting/frr/blob/9852228d1e87bdbad13e0fed8313203f00bf26af/zebra/zebra_netns_notify.c#L235
https://github.com/FRRouting/frr/blob/9852228d1e87bdbad13e0fed8313203f00bf26af/lib/frrevent.h#L114

[httpstorm]

@neheb
Changes:
Pass a copy of netnspath to basename, and use the result in all places that would call basename.
Let me know of any other changes are needed. I also added a git label for sending the patch upstream.

[neheb]

basename is

char *basename(char *path)

yet const char* are passed.

I wonder if the build warns because of this.

[httpstorm]

@neheb
My bad, it should be netnspath_basename = basename(strdupa(netnspath));. Yes, it does warn.

Before

arm-openwrt-linux-muslgnueabi-gcc -DHAVE_CONFIG_H -DSYSCONFDIR=\"/etc/frr/\" -DCONFDATE=0 -I.  -I./lib/assert -I. -I./include -I./lib -I.    -I/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/usr/include -I/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include -I/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify  -fms-extensions -fno-omit-frame-pointer -funwind-tables -Wall -Wextra -Wformat-nonliteral -Wformat-security -Wswitch-enum -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wbad-function-cast -Wwrite-strings -Wundef -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers  -I/Volumes/wrt3200/openwrt/staging_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/usr/include      -Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -mfloat-abi=hard -fmacro-prefix-map=/Volumes/wrt3200/openwrt/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/frr-9852228d1e87bdbad13e0fed8313203f00bf26af=frr-9852228d1e87bdbad13e0fed8313203f00bf26af -flto=auto -fno-fat-lto-objects -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro  -c -o zebra/zebra_netns_notify.o zebra/zebra_netns_notify.c
In file included from ./lib/zebra.h:16,
                 from zebra/zebra_netns_notify.c:7:
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h: In function 'snprintf':
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h:101:9: warning: format not a string literal, argument types not checked [-Wformat-nonliteral]
  101 |         return __orig_snprintf(__s, __n, __f, __builtin_va_arg_pack());
      |         ^~~~~~
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h: In function 'sprintf':
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h:110:17: warning: format not a string literal, argument types not checked [-Wformat-nonliteral]
  110 |                 __r = __orig_snprintf(__s, __b, __f, __builtin_va_arg_pack());
      |                 ^~~
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h:114:17: warning: format not a string literal, argument types not checked [-Wformat-nonliteral]
  114 |                 __r = __orig_sprintf(__s, __f, __builtin_va_arg_pack());
      |                 ^~~
zebra/zebra_netns_notify.c: In function 'zebra_ns_ready_read':
zebra/zebra_netns_notify.c:265:39: warning: passing argument 1 of 'basename' discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  265 |         netnspath_basename = basename(netnspath);
      |                                       ^~~~~~~~~
In file included from zebra/zebra_netns_notify.c:17:
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/libgen.h:9:16: note: expected 'char *' but argument is of type 'const char *'
    9 | char *basename(char *);
      |                ^~~~~~

After

arm-openwrt-linux-muslgnueabi-gcc -DHAVE_CONFIG_H -DSYSCONFDIR=\"/etc/frr/\" -DCONFDATE=0 -I.  -I./lib/assert -I. -I./include -I./lib -I.    -I/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/usr/include -I/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include -I/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify  -fms-extensions -fno-omit-frame-pointer -funwind-tables -Wall -Wextra -Wformat-nonliteral -Wformat-security -Wswitch-enum -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wpointer-arith -Wbad-function-cast -Wwrite-strings -Wundef -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers  -I/Volumes/wrt3200/openwrt/staging_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/usr/include      -Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -mfloat-abi=hard -fmacro-prefix-map=/Volumes/wrt3200/openwrt/build_dir/target-arm_cortex-a9+vfpv3-d16_musl_eabi/frr-9852228d1e87bdbad13e0fed8313203f00bf26af=frr-9852228d1e87bdbad13e0fed8313203f00bf26af -flto=auto -fno-fat-lto-objects -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro  -c -o zebra/zebra_netns_notify.o zebra/zebra_netns_notify.c
In file included from ./lib/zebra.h:16,
                 from zebra/zebra_netns_notify.c:7:
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h: In function 'snprintf':
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h:101:9: warning: format not a string literal, argument types not checked [-Wformat-nonliteral]
  101 |         return __orig_snprintf(__s, __n, __f, __builtin_va_arg_pack());
      |         ^~~~~~
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h: In function 'sprintf':
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h:110:17: warning: format not a string literal, argument types not checked [-Wformat-nonliteral]
  110 |                 __r = __orig_snprintf(__s, __b, __f, __builtin_va_arg_pack());
      |                 ^~~
/Volumes/wrt3200/openwrt/staging_dir/toolchain-arm_cortex-a9+vfpv3-d16_gcc-14.1.0_musl_eabi/include/fortify/stdio.h:114:17: warning: format not a string literal, argument types not checked [-Wformat-nonliteral]
  114 |                 __r = __orig_sprintf(__s, __f, __builtin_va_arg_pack());
      |                 ^~~

[BKPepe]

It looks like it is quite different from FRRouting/frr#15987 , which also tries to fix build errors for GCC14.

[httpstorm]

@BKPepe
That does nothing to address our build error. I tested to confirm.
Edit: If you like, I can submit my PR upstream once someone confirms it is good, then address any remaining issues with them, and once accepted, backport the results here.

[robimarko]

It would be great if you open a PR against FRR to upstream this

[httpstorm]

@robimarko @neheb
PR for upstream: FRRouting/frr#16155

[BKPepe]

It seems like upstream merged it. Great work! 👏 This is how it should be. Appreciated.

I will merge this once CI/CD succeeds.

[httpstorm]

@robimarko @neheb
Accepted upstream, so rebase on master and update PKG_RELEASE, which I previously forgot to do.

@BKPepe Thanks! :) tests completed